A high NOx reading of 1100 at both 1500 and 2500 RPM, often points to a lean condition in a Cutlass Ciera. A lean condition occurs when the air-fuel mixture has too much air and not enough fuel. While a plugged catalytic converter might be suspected, replacing it doesn’t always solve the problem. Faulty fuel injectors can be a culprit behind a lean condition, potentially contributing to high NOx emissions.
Using a GM Tech 1 scan tool, a crucial diagnostic tool for Cutlass Ciera, can perform an Idle Relearn procedure. This is often necessary after battery replacement or disconnection, as it resets the idle settings. However, if bad fuel injectors are the root cause, the Idle Relearn procedure might be ineffective until the injectors are replaced. A service manual specific to the model year, such as a 1992 Cutlass Supreme manual, outlines procedures like the GM Tech 1 Idle Relearn.
Fuel injectors can be susceptible to heat soak, especially as they age. As the engine warms up, heat soaked injectors can lose resistance, affecting their performance and potentially leading to a lean condition. A Cutlass Ciera running smoothly when cold but experiencing issues when warm might indicate heat soaked or faulty injectors. Symptoms might include stumbling, loss of power, or even stalling, particularly under load at higher RPMs (around 2500-3500).
Testing the fuel injectors with an ohmmeter can help confirm their condition. While an ohmmeter test can be helpful, driving the car when cold and then under load when warm provides crucial diagnostic information. If the car performs poorly when warm, especially under load, bad fuel injectors are highly likely. In cases like these, replacing the faulty injectors often resolves the issue. Remember, a properly functioning fuel injection system is crucial for optimal engine performance and emissions control in a Cutlass Ciera.
